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Listening to the breaths of 1,000 cells.

Listening to the breaths of 1,000 cells

Like a stone dropped into a lake, biochemical changes in a cell ripple across its sea of metabolism. And as different stones produce similar ripples, many biomolecules have common effects, for example, changing the rate at which mammalian cells turn food (glucose) and oxygen into energy and waste products, mostly lactic acid and carbon dioxide.

Using these products as reporter molecules, a team of scientists from Molecular Devices Corp. in Menlo Park, Calif., and Stanford University has developed a biosensor that measures the metabolism of as few as 1,000 cells under different chemical and physical conditions. The scientists say the biosensor might serve as an alternative for some animal testing and as a means for screening candidate drugs.

Called a silicon microphysiometer, the device monitors metabolism by measuring acidity changes of a nutrient bath that flows over tumor and other test cells stuck to a flat silicon base or immobilized in tiny wells micromachined into the base. The bath's acidity depends on the cells' explusion of lactic acid and carbon dioxide. When liquid flows through the biosensor, the acidity remains constant. Stopping the flow for several-minute periods, though, allows the acidic waste molecules to accumulate in amounts determined by the hormones, drugs or other test chemicals dissolved in the bath.

In the Oct. 13 SCIENCE, the researchers reported using their biosensor to screen a panel of eye irritants previously evaluated by the Draize Test, a consumer safety test in which chemicals are applied to the eyes of rabbits. The irritants depressed metabolism in test cells by amounts that closely parallel Draize test results. The researchers say that in addition to providing a possible alternative to in vivo toxicological tests and a tool for basic molecular biological studies, the biosensor may help doctors to identify new compounds that kill cancer cells or to choose which cancer drug to use with particular patients.
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Title Annotation:biomolecules
Publication:Science News
Date:Oct 28, 1989
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